Train-control system



Nov. 19, 1929. c. s. BUSHNELL TRAIN CONTROL SYSTEM Filed March 1, 1927 INVE TOR a k wu AT ORNEY m Patented Nov. 19, 1929 OFFEZCE CHARLES S. BUSHNELL, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK TRAIN-CONTROL SYSTEM Application filed March 1,

This invention relates, in general, to an automatic train control system, and has more particular reference to a properly protected reset device for use in such systems.

In some types of automatic control systems, a device responsive to traffic conditions is operated, upon a vehicle passing a wayside signal set at stop or caution, to give an automatic brake application, the device being .;0 arranged that after the signal in question has been passed, it is not automatically restored to its normal condition. In such circumstances, a resetting means is necessary for restoring the traffic control device to normal condition, in order to release the vehicle from the brake application.

There is a possibility, unless properly protected against, of using the reset device to orevent the automatic operation of the trafiic control device on passing a signal in its danger or caution position, and furthermore, of leaving the reset device in its operated position, instead of restoring it to normal.

With the above and other considerations 7 in mind, it is proposed, in accordance with this invention, to provide a reset device for an automatic train control system, which is properly protected against any such misuse as referred to above. More specifically, it 18 proposed to provide a reset device, operable only when the train is stationary, which operates to produce a brake application if a brake application be not already in effect at that time, upon operation of the reset device to restore the traffic responsive device to its normal position.

Further objects, purposes, and characteristic features of the present invention will appear as the description progresses, reference being had to the accompanying drawlng, showing, solely by way of example, one form of the invention. In the drawings:

Fig. l is a schematic showing of a control system embodying the present invention.

Fig. 2 shows, schematically, trackway control means.

Referring to the drawing, a section of trackway is shown constituted by track rails 1 separated into signal blocks, in the usual manner, by insulating joints 2, and equipped 1927. Serial No. 171,821.

with wayside signals 3, of the semaphore, or any other desired, type. i

The trackway portion of the present automatic control system includes an inductor 4 positioned near the entrance to each block, and furnished with means, such as choke coils 4E and a condenser 4", for example, controlled by arm 3 of the adjacent wayside signal, for varying its action, as is well understood by those versed in this particular art, and a more detailed explanation than what follows is deemed unnecessary for a proper understanding of the present invention.

The car-carried apparatus, carried by a car as represented diagrammatically by the Wheels and axles 5, includes a receiver 6, having primary coils P, and secondary coils S. The primary coils P are included in a circuit in series with a condenser 7, and a source of alternating current, such as the alternator 8, preferably generating alternating current of a frequency of about 360 cycles per second. The condenser 7 is so adjusted with reference to the coils P and the rest of the circuit, that the circuit in question is tuned to oscillate most freely at the frequency of the alternating current employed.

The secondary coils S are connected in series with each other and with a condenser 9 and windings 10 of a main relay MR having a core 11, preferably of laminated material, and a pivoted armature 12 biased to open position by a spring 13. The condenser 9 is likewise proportioned relative to the secondary coils S, the coils 10, and the other portions of the circuit, to tune the secondary circuit to oscillate most freely at the frequency of the alternating current employed.

In operation, the apparatus as thus far described, functions in the following manner. When a signal 3 is either at stop or caution it causes its inductor 4 to be active, by arm 3 open circuiting coils 4 and condenser 4", so that the receiver 6, upon passing over, but out of contact with, the inductor, in the manner usual in intermittent inductive train control systems, is so affected, due to changes in the characteristics of the magnetic circuits in question, i. e a reduction of the reluctance of magnetic paths, that the current flowing in the circuit including coils 10 of main relay MB, is reduced to Zero, or at least to such a small amount that the armature 12 is rei ractecl by the spring 13.

If the signal be in its clear position, the arm 3 so controls its particular inductor by close circuiting coils 4 and condenser 4", that the inductor has either no affect whatvoever on the receiver or actually increases the current flowing in the secondary circuit including the coils 10 of the main relay, so that a signal at clear can be passed without incurring any brake application. Of course the inductors and receivers are preferably formed of laminations, in order to prevent various losses such as due to eddy currents, due to the use of alternating current.

Connected to the armature 12, by means of aspring 14, and a rigid limiting latch 15, is a valve stem 16 carrying a valve 17 which controls a port 18, in valve housing 19, connected, at one side of the port 18, to atmosphere through the port 20, and at the other side, to the brake actuator pipe 21.

A pipe 22 branches off from the actuator pipe 21 and communicates with a valve housing 23 at one side of a port 24, while the housing at the other side of the port 24 communicates with atmosphere through a port 25.

The port 24 is normally closed by a spring pressed check valve 26, having an elongated stem 27 extending beyond one end of the housing a suitable distance.

A reset rod 28 is slidably arranged in guides 29 connected to some fixed structure, and at its lower end has a manual actuating knob 30, so positioned that upon actuation of the stem 28 the knob 30 will raise the stem 27, and with it the valve 26, to open the port 24 to thus connect pipe 22 to atmosphere through ort 25.

With the above described structure, after the main relay MR has been de-energized, as

, described above, thus permitting its armature 12 to be retracted by the spring 13, the valve 17 is moved away from its port 18 to thereby connect the actuator pipe 21 to atmosphere through the port 20, and impose an automatic rake application on the train.

After passing the particular inductor in question, a potential is again impressed across, and current again flows through, the circuit including the relay coils 10, but due to the dropped away position of armature 12, this circuit is now detuned at the frequency of the current supplied, and hence the current is cut down in amount sufficiently to prevent an automatic pick-up of the armature 12 due to the attraction of the core 11. Of course, in a relay energized by electrical energy, the pick up current is larger than the current required to hold the armature up, and in the present case this effect is added to that explained above as due to detuning. This detuning has much the same effect on the pick up characteristics of the relay as would the insertion of a very high current limiting resistance in a direct current energizing circuit. It is thus necessary to pick up the armature 12 in some other manner, and this is accomplished by pressing on the knob 30., to force the end of the rod 28 against the armature and rock it back into attracted position. In so resetting the armature, the knob 30 raises the stem 27, and vents the actuator pipe 21 by Way of pipe 22 and ports 24 and 25.

When resetting relay MR, since the brakes are already applied, it is no disadvantage to vent the actuator pipe 21, as described, through the medium of the knob 30 and stem 27. Should the engineman, however, attempt to defeat the automatic feature of this train control system, by pressing upwardly on, or tying, the knob 30, before or during passage of the receiver over an inductor in its active condition, an automatic brake application would be incurred.

In the same manner, after having reset the armature 12 after an automatic brake application, before the brakes can be released it is necessary that the reset device be restored to its normal lowered position, since otherwise the brakes remain set due to the actuator pipe 21 being vented through port 25 to atmosphere.

It will thus be seen that with the arrangement shown and described, the reset device is protected against misuse and against being left in its operated position after a resetting operation.

In the above description, only so much of an automatic train control system has been shown and described, as is deemed necessary for a clear understanding of the present invention. It is obvious that the present system could also include any usual or desired form of acknowledging device whereby the engineman if alert, could run past an active inductor without incurring an automatic brake application, providing he properly acknowledged, as is well understood by those versed in this particular art.

While the present invention has been described in connection with an automatic inductive alternating current train control sys tern it is believed quite obvious that it might find numerous applications in other connections.

The above rather specific description of one form of the present invent-ion has been given solely by way of illustration, and is not intended, in any manner whatsoever, in a limiting sense. Obviously, the invention can assume numerous different physical embodiments and is susceptible of various modifications, all such embodiments and modifications are intended to be covered by this invention, as come within the scope of the appended claims.

Having described my invention, I now claim 1. In a train control system, a relay having an armature, and controlled in accordance with traffic conditions ahead, a brake pipe, means controlled by the relay armature for venting: the pipe to thereby cause an automatic brake application when the armature drops away, and reset means operable to mehanically restore the armature to picked up position and to simultaneously vent said brake pipe.

2. In a train control system, a relay controlled in accordance with t-raflic conditions ahead, a relay armature, a brake pipe, a valve controlled by the relay armature for venting the pipe to thereby cause an automatic brake application when the armature drops away, a second valve, and reset means manually perable to restore the armature to picked up position and simultaneously operate said second valve to vent said brake pipe.

3. In'a train control system, a relay normally energized by alternating current hrough a circuit tuned when the relay is in attracted position to the frequency of the alternating current employed for energizing such circuit and controlled in accordance with traffic conditions ahead, a relay armature, a brake pipe, means controlled by the relay armature for venting the pipe to thereby cause an automatic brake application when the armature drops away, and detunes said tuned circuit and reset means operable to re- :tore the armature to picked up position and simultaneously vent said brake pipe.

4. In a train control system, a relay controlled through a tuned circuit in accordance with traffic conditions ahead, a relay armature, a brake pipe, means controlled by the relay armature for venting the pipe to thereby cause an automatic brake application when the armature drops away, a resilient connection between the armature and venting neans, and reset means operable to restore the armature to picked up position and simultaneously vent said brake pipe.

5. In a train control system, a relay controlled by traflic conditions, a tuned energizlng circuit for the relay, a brake actuator pipe, a valve for venting the pipe and causing an automatic brake application, a relay armature operably associated with said valve to cause venting of the pipe on de-energization of the relay, and reset means operable to simultaneously reset the relay armature and vent the said pipe.

6. In a train control system, a relay controlled by traflic conditions, a tuned energizing circuit for the relay, a brake actuator pipe, a valve for venting the pipe and causing an automatic brake application, a relay armature operably associated with said valve to cause venting of the pipe on de-energization of the relay, a vent valve controlling connection of the pipe to atmosphere, and a reset rod manually operable to move the armature to picked up position and to simultaneously open said vent valve.

7. In a train control system, a relay controlled by traflic conditions, a tuned energizing circuit for the relay, a brake actuator pipe, a valve biased to closed position, for venting the pipe and causing an automatic brake application, a relay armature operably associated with said valve to cause venting of the pipe on de-energization of the relay, a vent valve biased to closed position and controlling connection of the pipe to atmosphere, and a reset rod manually operable to physically move the armature to picked up position and to simultaneously open the vent valve.

In testimony whereof I afiix my signature.

CHARLES S. BUSHNELL. 

